Bias voltage supplying circuit.

摘要

A bias voltage supplying circuit for supplying a bias voltage includes first and second PNP type transistors (Q1, Q2) having emitters coupled to a first power source terminal and bases connected to each other, where the first PNP type transistor has a collector coupled to the base thereof, first and second NPN type transistors (Q3, Q4) having collectors respectively connected to collectors of the first and second PNP type transistors, emitters coupled to a second power source terminal and bases connected to each other, where the second NPN type transistor has the collector connected to the base thereof, and a diode part (D) coupled between the emitter of the second PNP type transistor (Q2) and the base of the second NPN type transistor (Q4). The diode part (D) has an anode end coupled to the emitter of the second PNP type transistor and a cathode end coupled to the base of the second NPN type transistor, and the diode part has a forward voltage drop VD which is less than a voltage VS across the first and second power source terminals. The voltage VS is less than a sum of the forward voltage drop VD and a base-emitter voltage VBE of the second NPN type transistor.